Conversion Mode Research Articles

Analysis Model for Damage of PBO Composite Laminate Target by High-Velocity Projectile Penetration

Poly-p-phenylene benzobisoxazole (PBO) fiber is a new fiber with high ballistic performance, such as excellent heat and flame resistance and super mechanical properties. Consequently, increasing attention has been paid to its applications in the field of ballistic resistance. To identify the damage mechanism of PBO composite target caused by the high-velocity penetration of cylindrical projectiles and the energy conversion mode involved in the penetration process, this paper constructs a target damage engineering analysis model using the energy method in combination with stress wave propagation and projectile motion analysis. The residual velocity of the steel cylindrical projectile after perforating a PBO composite laminate is measured through ballistic tests, and it is compared with the value predicted by the analysis model. Comparison results show that the predicted value by the model is in good agreement with the measurement, with an error of less than 2.6%, thereby proving the validity of the constructed analysis model.

Tunable metasurfaces for seismic Love wave manipulation: A theoretical study

Seismic Love waves are horizontally polarized surface waves propagating within an overlying layer, which have been shown to pose potential hazards to infrastructures. In this study, we propose an original analytical formulation to investigate the interaction between seismic Love waves and a metasurface that is composed of a cluster of tunable anti-plane resonators. The formulation utilizes the Green's function of a layered half-space subjected to a surface SH source, to describe both the source-induced incident field and the resonator-excited scattered field. Based on the multiple scattering theory, we obtain the total wavefield of the layered half-space equipped with surface resonators by coupling the incident field and the scattered field. Besides, a closed-form dispersion relation governing the hybrid Love waves is derived by utilizing the effective medium approximation. We demonstrate the capabilities of our analytical formulation by modelling Love waves propagating across a pair and a cluster of resonators, evidenced by some complex phenomena (e.g., surface-to-bulk wave conversion and higher-order hybridized surface modes). The hybridization features of different Love modes and metasurface resonances are clearly revealed. We anticipate the proposed tunable metasurface and the formulation can shed light on versatile control of Love wave propagation.

Tunable High‐Field Terahertz Radiation from Plasma Channels

AbstractTunable broadband terahertz (THz) sources with power at the gigawatt level are desirable for many applications. A scheme to generate such THz emission by off‐axially injecting a weakly relativistic ultrashort laser into a parabolic plasma channel is presented. By utilizing two‐dimensional particle‐in‐cell simulation, it is demonstrated that there are two major physical mechanisms involved, i.e., linear mode conversion from laser wakefields and the electromagnetic waveguide mode excitation inside the plasma channel. The two radiation modes can lead to linearly polarized and radially polarized THz emissions, respectively, with distinct frequency spectra and spatial distributions. It is found that they predominate alternatively with the change of the plasma channel length. For a given plasma channel, one can switch the radiation modes by adjusting the injection position and the injection angle of the laser pulse. In particular, the radiation mode of the linear mode conversion can produce THz pulses with the peak amplitude of sub‐GV cm−1 with the energy conversion efficiency ≈10−3, even though the peak power of the incident laser is just at the terawatt level. The scheme provides a powerful THz source with tunable intensity, spatial distributions, spectra, and polarizations by simply adjusting the injection conditions of incident laser pulses.

Effective hydrogen generation using water-n-hexane-ZrO2 system: Effect of temperature and radiation irradiation time

There is a great demand for economic green hydrogen fuel production and, consequently, hydrogen generation by water radiolysis of a hexane-water system on ZrO2 surface is presented at various temperatures. The radiation-catalytic decomposition of the hexane-water had increased at high temperatures i.e. ranging from 300 to 673 K. It caused an increase in the yield of hydrogen production in the radiation-catalytic decomposition of hexane-water. It was observed that at a temperature of T = 673 K a chain mode of conversion of the key products of hexane-water resulted in molecular hydrogen. Finally, the maximum yield of hydrogen was 188.5 molecule/100 eV with n-ZrO2 + C6H14(ads)-water (0.003 g: 0.0051 g: 0.0015 g) at 673 K.

Absorption of methionine sources in animals-is there more to know?

This literature review evaluates the absorption of methionine (Met) sources such as 2-hydroxy-4-methylthiobutyric acid (HMTBa), its calcium salts (HMTBa-Ca), and DL-methionine (DL-Met) by focusing on the state of knowledge regarding the absorption mechanism, experimental methodology, and factors affecting their absorption. The 2 Met sources differ in mechanism and site of absorption due to differences in their chemical characteristics and enzymatic conversion. This review addresses diffusion- and transport-mediated absorption systems for amino acids and carboxylic compounds, best elucidated by invitro, exvivo, and invivo experimental models. Opportunities and limitations in the use of radioisotopes to depict absorption sites as well as host and microbial metabolism are described. Physiological and environmental conditions that lead to changes in gut absorptive capacity and the impact of Met source absorption are also evaluated. This review concludes that any comparison between HMTBa and DL-Met should consider their different behaviors during the absorption phase. Hence, the chemical characteristics of these 2 molecules entail different absorption sites and mechanisms, from passive absorption in the case of HMTBa and HMTBa-Ca to active transporters for DL-Met, HMTBa, and HMTBa-Ca. In addition, the different conversion modes of these 2 molecules further differentiate their absorption modes. Considering these important differences, it is easier to understand the apparent divergence between the conclusions of existing publications. When comparing these 2 molecules, it is recommended to properly adapt to the conditions under which the absorption of Met sources is evaluated.

Dual function tunable THz metamaterial device possessing broadband absorption and polarization conversion

Based on the phase transition properties of vanadium dioxide (VO2), a novel tunable metamaterial device with functions of broadband absorption and broadband polarization conversion is constructed. The proposed structure operates in the broadband absorption mode when the VO2 is in the metallic state. The simulation results demonstrated that the absorbance can achieve more than 90% with a relative bandwidth of 76.9% in the frequency range of 1.80-4.05THz. When VO2 is in the insulating state, the proposed structure operates in the broadband polarization conversion mode. In the frequency range of 1.68-3.79THz, it can efficiently convert the incident linearly polarized terahertz (THz) wave into its cross-polarized state. The polarization conversion ratio (PCR) is above 90% and the relative conversion bandwidth is larger than 77.1%. Furthermore, for the two operating modes, it has acceptable tolerance of incident angles and polarization angles. These advantages make the proposed VO2-based dual-functional metamaterial device have potential applications in many THz areas, such as absorption, polarization conversion, imaging, and so on.

Ecmtool: fast and memory-efficient enumeration of elementary conversion modes.

Characterizing all steady-state flux distributions in metabolic models remains limited to small models due to the explosion of possibilities. Often it is sufficient to look only at all possible overall conversions a cell can catalyze ignoring the details of intracellular metabolism. Such a characterization is achieved by elementary conversion modes (ECMs), which can be conveniently computed with ecmtool. However, currently, ecmtool is memory intensive, and it cannot be aided appreciably by parallelization. We integrate mplrs-a scalable parallel vertex enumeration method-into ecmtool. This speeds up computation, drastically reduces memory requirements and enables ecmtool's use in standard and high-performance computing environments. We show the new capabilities by enumerating all feasible ECMs of the near-complete metabolic model of the minimal cell JCVI-syn3.0. Despite the cell's minimal character, the model gives rise to 4.2×109 ECMs and still contains several redundant sub-networks. ecmtool is available at https://github.com/SystemsBioinformatics/ecmtool. Supplementary data are available at Bioinformatics online.

Scale-to-scale energy transfer in rarefaction-driven Rayleigh–Taylor instability-induced transitional mixing

The rarefaction-driven Rayleigh–Taylor instability-induced mixing flow is numerically investigated via large eddy simulation. Prior analyses of interfacial diffusion are conducted to clarify the scale-to-scale transfer of kinetic energy during the laminar-to-turbulent transition. The statistical characteristics, including subgrid-scale (SGS) turbulent kinetic energy and SGS stresses, are outlined and highlight the mechanical production as well as pressure-related effects. Further inspection reveals that the relative intensity of SGS backscatter is somewhat noticeable, particularly for the transition onset, and the large-scale pressure-dilatation work is regulated through volumetric compression and expansion. Joint probability density function and the conditional averaging approaches both manifest that SGS backscatter is extremely associated with properties of the surrounding flow expansion induced by quadrupolar vortex structures. Furthermore, investigations on the effects of SGS backscatter on eddy viscosity are performed, and a regime classification, illustrating the relationship between various energy conversion modes and signs of the eddy viscosity, is provided. It is found that there is a significantly strong correlation between SGS backscatter and negative eddy viscosity; meanwhile, the volumetric compression and expansion tend to modulate the scale-to-scale energy transfer throughout the transitional process.

Switching modeling and bumpless transfer tracking control for the conversion mode of tilt-rotor aircraft

The modeling and state tracking control for the conversion mode of tilt-rotor aircraft are investigated with a switching modeling method and a bumpless transfer technique. Based on the Euler equation and the Blade element theory, the nonlinear model of conversion mode is deduced to illustrate the features of the tilting process. Afterward, the switching modeling method settles the linearization problem of the nonlinear control with an uncontrollable nacelle inclination signal. Meanwhile, it also transfers the conversion mode control issue to a reference state tracking control problem of switched linear systems. In addition, the [Formula: see text] control is adopted to restrain the external disturbances, and the controller with bumpless transfer performance is designed to overcome the control jump at switching instants. Finally, an example of XV-15 tilt-rotor aircraft is proposed to illustrate the effectiveness of the developed method.

Screw electromechanical hydrolyzer for processing poultry by-products

The use of keratin-containing products in various industries, including agriculture, cosmetics, and biomedicine requires solving the urgent problem of improving the methods and means of hydrothermal hydrolysis of keratin waste. The purpose of this work was to study the screw electromechanical hydrolyzer to provide modes of efficient conversion of keratin waste into a useful product with added value. The research was based on the basic principles of electrodynamics, heat and mass transfer, mathematical modeling by the finite element method, and experimental verification of the multiphysical parameters of the electromechanical hydrolyzer. The experimental model of the electromechanical hydrolyzer was used to determine the optimal conditions for hydrothermal hydrolysis of keratin waste in terms of thermal conditions, raw material transportation, pressure, and magnetic field effects. As a result of the processing, bulk hydrolyzed brown feather flour with a specific odor was obtained. According to the size of the electromagnetic system of the experimental sample, a mathematical model for studying thermal and electromagnetic processes was built. The regularities of the spatial distribution of magnetic induction for the cross-section, axial distribution on the surface of the screw, and the upper faces of the screw winding of an electromechanical hydrolyzer were determined. Three-dimensional images of the heating of the screw and the screw electromechanical hydrolyzer itself were obtained. By comparing the results of mathematical modeling and empirical studies, the adequacy of the mathematical model was confirmed. The results of the research can find application in the field of animal husbandry in the production of feed additives of increased digestibility for the needs of feeding agricultural animals and poultry

High-Speed Fully Differential Two-Step ADC Design Method for CMOS Image Sensor

The application requirements of high frame rate CMOS image sensors (CIS) in the industry have not been satisfied due to the speed limitations in traditional single-slope and serial two-step analog-to-digital converters (ADCs). In this paper, a high-speed fully differential two-step ADC design method for CIS was proposed. The proposed method was based on differential ramp and time-to-digital conversion (TDC) technology. A parallel conversion mode was formed that is different from serial conversion, and the robustness of the system was ensured due to the existence of differential ramps. Aiming at the inconsistency between traditional TDC technology and single-slope ADC, a TDC technology based on level coding was proposed. The proposed technology achieves the TDC in the last clock cycle of analog-to-digital conversion, and realized a two-step conversion process at another level. This paper presents a complete circuit design, layout design, and test verification of the proposed design method based on the 55 nm 1P4M CMOS experimental platform. Under the design environment of the analog voltage of 3.3 V, the digital voltage of 1.2 V, the clock frequency of 100 MHz, and a dynamic input range of 1.6 V, this design was a 12-bit ADC with a conversion time of 480 ns, column-level power consumption of 62 μW, differential nonlinearity (DNL) of +0.6/-0.6 LSB, and integral nonlinearity (INL) of +1.2/-1.4 LSB. Furthermore, it achieved a signal-to-noise distortion ratio (SNDR) of 70.08 dB. The proposed design provided a large area array with a high frame rate, and compared with the existing advanced single-slope ADC, its conversion speed increased by more than 52%. It provides an effective solution for the implementation of high frame frequency CIS.

Active terahertz beam deflection based on a phase gradient metasurface with liquid crystal-enhanced cavity mode conversion.

Active manipulation of terahertz (THz) beam deflection and intensity is highly desired for possible applications in wireless communication, radar, and remote sensing. Here, by integrating the phase-gradient metasurfaces and tunable liquid crystal materials, we demonstrate an active THz beam deflection device based on polarization mode conversion. The resonant modes in the photonic cavity formed by the double-layer metasurface and the tunable anisotropic liquid crystal material in the cavity not only improve the polarization conversion efficiency of the device, but also actively regulate the resonance matching conditions. As a consequence, a beam deflection of 47.5° with 50% diffraction intensity at 0.69 THz is achieved in the x-to-y polarization conversion mode, and this beam can be actively modulated with an ultrahigh modulation depth of 99.6% by rotating the anisotropic optical axis of liquid crystals. Moreover, the proposed device can also work as the deflection of 32.5° in the y-to-x polarization conversion mode at 0.94 THz with a maximum diffraction intensity of 38% and an intensity modulation depth of 97.8%. This work provides a new approach based on liquid crystal photonic devices for wavefront manipulation and active modulation for THz waves.

Determination of methods of achieving the energy savings through mathematical modeling of static and dynamic modes of electromagnetic energy conversion in asynchronous motors used in feed crushers

The article covers the ways of achieving energy savings by controlling the speed of asynchronous electric motors in a frequency method. Frequency control is economical because it increases the efficiency and reduces power loss by adjusting the speed of the asynchronous motor.

Experimental Study on the Control of the Positions of the Cycle Isotherms of the Heat Pump in the Air Handling Unit

Abstract The use of air-to-air heat pumps in modern air handling units is becoming more popular for building heating and cooling supply. However, the constantly changing state of outdoor air (temperature, humidity) means that energy conversion modes of heat pumps need to be flexible and able to efficiently respond to ambient air parameters. The ability to adapt to changes in ambient air conditions in an efficient and rational manner is a crucial factor to consider when selecting the operating mode and control of energy transformers. Modern commercial heat pumps typically have two control degrees of freedom, which include a variable-speed compressor and an electronic expansion valve. This combination of control components has previously helped to improve the seasonal efficiency of heat pumps. However, for a long time, focus was placed mainly on refining electronic control tools, without considering how changes in the thermodynamic cycle of heat pumps are correlated with energy demands for air preparation that correspond to outdoor temperatures. The authors of the article propose introducing an additional component into traditional heat pump control measures to provide a third degree of freedom for the cycle control. The experiments were conducted to assess the impact of the heat pump system volume on its thermodynamic operating cycle and it was found that the system volume parameter has the potential for regulation capabilities in controlling the operation of a heat pump. This technological solution has the potential to increase efficiency indicators of the air preparation process and warrants further development and study.

Applications of sulfonyl hydrazides in radical cyclization of alkenes.

Radical cyclization is regarded as a powerful and promising strategy for the assembly of diverse important cyclic structures because of its high atom- and step-economy. As excellent radical acceptors, alkenes offer two potential directions, pushing the research domain of radical cyclization. In this context, as a radical precursor, sulfonyl hydrazide plays an important role in accomplishing radical cyclization of alkenes in a facile and efficient way. This review focuses on the applications of sulfonyl hydrazides in radical cyclization of alkenes, which generally has two radical conversion modes, sulfonyl radicals and sulfoxide radicals. In particular, the section of sulfonyl radicals consists of eight parts containing aromatic rings, alkenes, alkynes, cyanides, aldehydes, carboxylic acids, amides, and small ring compounds, according to the objects of cyclization after addition with alkenes. Within each category, representative instances are presented and discussed in terms of their general mechanistic perspectives when needed.

Dissipativity based anti-disturbance event-triggered tracking control of time-delay switched linear systems and its application to the conversion mode of XV-15 tilt-rotor aircraft

Dissipativity based anti-disturbance event-triggered tracking control of time-delay switched linear systems and its application to the conversion mode of XV-15 tilt-rotor aircraft

Aptamer-functionalized two-photon SiO2@GQDs hybrid-based signal amplification strategy for targeted cancer imaging.

Targeted imaging is playing an increasingly important role in the early detection and precise diagnosis of cancer. This need has motivated research into sensory nanomaterials that can be constructed into imaging agents to serve as biosensors. Graphene quantum dots (GQDs) as a valuable nanoprobe show great potential for use in two-photon biological imaging. However, most as-prepared GQDs exhibit a low two-photon absorption cross-section, narrow spectral coverage, and "one-to-one" signal conversion mode, which greatly hamper their wide application in sensitive early-stage cancer detection. Herein, a versatile strategy has been employed to fabricate an aptamer Sgc8c-functionalized hybrid as a proof-of-concept of the signal amplification strategy for targeted cancer imaging. In this study, GQDs with two-photon imaging performance, and silica nanoparticles (SiO2 NPs) as nanocarriers to provide amplified recognition events by high loading of GQD signal tags, were adopted to construct a two-photon hybrid-based signal amplification strategy. Thus, the obtained hybrid (denoted SiO2@GQDs) enabled extremely strong fluorescence with a quantum yield up to 0.49, excellent photostability and biocompatibility, and enhanced bright two-photon fluorescence up to 2.7 times that of bare GQDs (excitation at 760 nm; emission at 512 nm). Moreover, further modification with aptamer Sgc8c showed little disruption to the structure of the SiO2@GQDs-hybrid and the corresponding two-photon emission. Hence, SiO2@GQDs-Sgc8c showed specific responses to target cells. Moreover, it could be used as a signal-amplifying two-photon nanoprobe for targeted cancer imaging with high specificity and great efficiency, which exhibits a distinct green fluorescence compared to that of GQDs-Sgc8c or SiO2@GQDs. This signal amplification strategy holds great potential for the accurate early diagnosis of tumors and offers new tools for the detection a wide variety of analytes in clinical application.

Macrophage cell membrane-based nanoparticles: a new promising biomimetic platform for targeted delivery and treatment

Synthetic nanoparticles with surface bioconjugation are promising platforms for targeted therapy, but their simple biological functionalization is still a challenging task against the complex intercellular environment. Once synthetic nanoparticles enter the body, they are phagocytosed by immune cells by the immune system. Recently, the cell membrane camouflage strategy has emerged as a novel therapeutic tactic to overcome these issues by utilizing the fundamental properties of natural cells. Macrophage, a type of immune system cells, plays critical roles in various diseases, including cancer, atherosclerosis, rheumatoid arthritis, infection and inflammation, due to the recognition and engulfment function of removing substances and pathogens. Macrophage membranes inherit the surface protein profiles and biointerfacing properties of source cells. Therefore, the macrophage membrane cloaking can protect synthetic nanoparticles from phagocytosis by the immune cells. Meanwhile, the macrophage membrane can make use of the natural correspondence to accurately recognize antigens and target inflamed tissue or tumor sites. In this review, we have summarized the advances in the fabrication, characterization and homing capacity of macrophage membrane cloaking nanoparticles in various diseases, including cancers, immune diseases, cardiovascular diseases, central nervous system diseases, and microbial infections. Although macrophage membrane-camouflaged nanoparticles are currently in the fetal stage of development, there is huge potential and challenge to explore the conversion mode in the clinic.

Self-organized structures induced by external white noise and nanosized levels of their formation in the non-crystalline As-S(Se) semiconductor systems

Discussed in this paper are the singularity and self-organizing effect of instability and randomness under the influence of external white noise on formation of non-crystalline materials. The random nature of the receiving medium together with the disorganizing effect was found to be capable to initiate formation of qualitatively new self-organized structures in non-crystalline solids. Also analyzed in the paper is the effect of a random temperature field applied to the melt during the cooling process in non-crystalline As-S(Se) semiconductor systems. The conditions for a non-crystalline system in a fluctuating external environment to adjust its properties to the average properties of the environment and to correspond to the deterministic case were identified. Furthermore, the conditions for non-additive reaction of the system to a random environment and formation of a new mode of energy conversion in the self-organized structure at the nanoscale level are determined. The spectrum of the structures created in this way is more diverse as compared to the spectrum corresponding to respective deterministic conditions.

Effects of energy-dependent scatterings on fast neutrino flavor conversions

Neutrino self-interactions in a dense neutrino gas can induce collective neutrino flavor conversions. Fast neutrino flavor conversions (FFCs), one of the collective neutrino conversion modes, potentially change the dynamics and observables in core-collapse supernovae and binary neutron star mergers. In cases without neutrino-matter interactions (or collisions), FFCs are essentially energy independent, and, therefore, the single-energy treatment has been used in previous studies. However, neutrino-matter collisions, in general, depend on neutrino energy, suggesting that energy-dependent features may emerge in FFCs with collisions. In this paper, we perform dynamical simulations of FFCs with isoenergetic scatterings (emulating nucleon scatterings) under multienergy treatment. We find that cancellation between in- and outscatterings happens in the high-energy region, which effectively reduces the number of collisions and then affects the FFC dynamics. In fact, the lifetime of FFCs is extended compared to the single-energy case, leading to large flavor conversions. Our result suggests that the multienergy treatment is mandatory to gauge the sensitivity of FFCs to collisions. We also provide a useful quantity to measure the importance of multienergy effects of collisions on FFCs.